1. Field of the Invention
This invention relates generally to aircraft guidance, and more particularly to a method and apparatus for providing automatic lateral guidance for an aircraft with respect to a directional radio beam during aircraft rollout upon landing.
2. Description of the Prior Art
A number of different types of systems have been heretofore developed for controlling the lateral guidance of an aircraft during rollout as it approaches a directional radio beam. Such systems typically operate in the terminal phase of an aircraft landing to align the flight path of the aircraft with the runway centerline by means combining localizer deviation signals with guidance parameters available from the aircraft's inertial guidance system and flight control computer. However, prior art systems have been subject to inducing unacceptable lateral deviations from the intended path once the aircraft is on the ground. Typical of the dynamic control complications introduced by the prior art is the decreased inherent stability of the aircraft as its ground velocity decreases due to the decreasing effectiveness of the control surfaces in controlling the aircraft path. Prior art guidance systems have suffered from overshoot, oscillation, or excessive lateral acceleration. The present invention relates to an improvement in rollout apparatus and methods by providing a system for generating steering control signals to continuously control subsequent lateral deviations from the intended flight path and to command the rudder and nosewheel to align the longitudinal axis of the aircraft with the runway centerline while minimizing oscillation and overshoot. The present ground rollout invention utilizes a runway command control law to command an optimal path for an aircraft to attempt to follow as it moves toward the center of the runway.